1. Field of the Invention
The present invention relates to a method of and an apparatus for rolling directly coupled with a continuous casting apparatus wherein a thin-slab continuous casting machine and a rolling machine are arranged in series and a slab produced by the continuous casting machine is directly rolled without being sheared.
2. State of the Related Art
As reported in Japanese Patent Unexamined Publication No. 60-87903, continuous casting-directly-coupled rolling facilities in which a continuous casting machine and a rolling machine are directly coupled with each other and a slab produced by the continuous casting machine is directly rolled without being sheared bring about large advantages in improving the production yield and energy saving.
With continuous casting-directly-coupled rolling facilities such as those disclosed in Japanese Patent Unexamined Publication No. 60-87903, a large number of machines, including a width rolling machine, a reduction rolling machine constituted by a multiplicity of stands, a cooling apparatus for a strip after reduction, a shearing machine, and a coiler for taking up final hot-rolled products, are arranged downstream of a continuous casting machine.
Frequently, there are cases where these machines disposed downstream of the continuous casting machine have to be shut down during an operation due to failures, such as a shortage of slabs during rolling or a failure in coiling.
In addition, if surface roughening occurs in a mill roll used in the rolling machine and rolling is continued with such a roll, harmful flaws are caused in the surface of the product which will be deprived of its commercial value, so that it is necessary to stop the rolling machine and replace the roll with a new one.
As described above, due to the situation of each machine being downstream and directly coupled with the continuous casting machine, cases can occur where the machines have to be stopped irrespective of the operating condition of the continuous casting machine. In such a case, since casting cannot be continued, the molten metal prepared for casting by the continuous casting machine is wasted.
In particular, with recent continuous casting machines, the amount of molten metal used in one cycle of casting is large at 100 to 200 tons, and an immense damage is incurred if such a large amount of molten metal is discarded due to the above-described reasons.
Japanese Patent Unexamined Publication No. 56-144805 discloses rolling facilities in which a continuous casting machine and a rolling machine are directly coupled with each other, and which employs a technique in which, when trouble, such as damage to a roll, occurs in a group of rolling stands, the operation is backed up by other normal rolling stands and the normal operation is continued without using the faulty rolling stand. However, the group of rolling machine stands disclosed therein are merely arranged as a group of rolling machines requiring a multiplicity of rolling machines, the arrangement being no different from a conventional one in which both a hot rolling machine and a cold rolling machine are disposed with a cooling apparatus interposed therebetween. As a result, they do not serve the originally intended purposes of the continuous casting-directly-coupled rolling facilities in which high-temperature slabs produced continuously are rolled into final products by a group of rolling machines on a small number of stands.